Due to increasing reliance on network-accessible computers, network security has become a major issue for organizations and individuals. To help ensure the security of their computers, organizations and individuals frequently install security devices between public networks and their private networks. A goal of such security devices is to prevent unwanted or malicious information from the public network from affecting devices in the private network.
Unfortunately, network security devices, like other devices, may fail. For example, a software or hardware problem or a power fault within a security device may cause all or a portion of the security device to stop functioning. When a security device fails, all network traffic flowing between the public network and the private network may cease. For an enterprise that depends on such network traffic this may be unacceptable, even if this failure occurs only for a short time. To minimize the chance of a failure causing all network traffic to cease, a backup security device may be installed. Thus, if the security device that has primary responsibility for performing the security services (i.e., the master security device) fails, the backup security device may be quickly substituted for the master security device. In other words, the failing security device “fails over” to the backup security device. After failing over to the backup security device, the backup security device becomes the master security device.
The process of failing over from a master to a backup security device may be computationally expensive and may cause significant delays. One reason for this is because, after failover, the backup security device is often required to reestablish network sessions with large numbers of client devices in the public and private networks. Because of the computational complexity of cryptography, these delays may be made worse if the backup security device must reestablish secure network sessions.